Multiple control



H. F. CLARK Qct. 19, 1940 MULT I PLE CONTROL Filed Jan. 29, 1945 bill-i dbl! liUU i l Patented Oct. 19, 1948 MULTIPLE CONTROL Harry F. Clark, Oakwood, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application January 29, 1943, Serial No. 473,892

5 Claims. (Cl. 200-122) 1 This invention relates to multiple control devices in which only under one circumstance there is an interlocking control.

In single phase starting devices it is normally 2 nent magnet provides a snap action and also insures that when both the starting and overload controls trip open, they will reset simultaneously. This particular application of magnetic control desired that the starting and overload controls 5 is n t confined the particular S a System operate independently. However, when the startshown but may be u e Whenever Separate armaing device moves to its running position and the tures to separate control may be ope te to Conoverload device trips open it is desired that the tact each other in a magnetic field and it is deoverload device either be prevented from returnsired that they be released simultaneously. ing to closed position before the starting control In Fig. 1 there is shown a split phase motor returns to the starting position or an arrangedesignated by the reference character 420 proment made by which the starting control will revided with a main Wind 4 d a Phase Windturn to starting position simultaneously with the ing 424 connected by a common Junction to the closing of the overload control. While this sisupply conductor 428. The other supply conducmultaneous return is shown applied to the starttor 428 is connected to a connector 438 mounted. ing and overload protection of an electric motor upon the base 434 of insulating material. This, it is also applicable to other applications where connector 438 carries a stationary contact 440 va simultaneous return is required. engaged by a movable contact 442 carried upon' 1 It is therefore an object of my invention to the free end of a bimetal strip 444 which is an- I provide a simple magnetic device which is so archored at its lower end in cantilever fashion by ranged to provide a snap-action in opening the means of a bracket 445 to the base 434. The contacts and which also provides a means for movable contact 442 upon the bimetal strip 444 insuring simultaneous reclosing of the contact connects the upper end of an electric heater 438 devices. to the adjacent part of the bimetal strip 444.

It is another object of my invention to provide The other end of the electric heater 436 exa simple magnetic means for insuring the operatends directly to the connector 414 supporting the tion of the two controls at the same time. back contact 416. The connector 414 also con These objects are attained by providing an armeets to one end of an electric heater 482, the rangement in which between the poles of a simother end of which is fastened to the yoke of a pie U-shaped permanent magnet are separate U-shaped bimetal member 480. The yoke of this armatures connected to the starting control and U-shaped bimetal member 480 is received within the overload protector. The starting control and a recess 433 provided in the base 434. One leg the overload protector are so arranged that when 459 of the bimetal 460 is upon the bottom side both trip open, their armatures will contact and of the base 434 and is fastened to a support 458 be located in series with the field so that when 35 extending from the base 434. The upper leg 48! either resets and its armature breaks away from of the bimetal 480 carries a movable starting, the other armature, the other control will reset contact 410 which also fastens the pig-tail clip. and, in fact both will always reset simultaneously. 412 to the leg 46! for connecting the pig-tail con- Further objects and advantages of the present nection 484 to the movable contact 410. The invention will be apparent from the following deother end of the pig-tail connection is connected scription, reference being had to the accompanyto the pig-tail clip 488 which is connected by the ing drawings wherein a preferred form of the conductor 488 to the other end of the main presentinventionis clearly shown. winding. A stationary starting contact 418 is' In the drawings: supported by the connector 480 which is con- Fig. 1 is a, plan view of a form of my starting nected by the conductor 482 to the other end and overload control connected diagrammatically of the phase winding 424. f to a diagrammatic split phase motor; A cover 90 fits over the top of the base 434 but Fig. 2 is a sectional view taken along the lines allows the lower leg 459 to be exposed to the en- 2-2 of Fig. 1; vironment air. When current flows through the Fig. 3 is a sectional view taken along the lines conductor 428 to the stationary contact 440 it 3-3 of Fig. 1; and will flow through the heater 438 thereby heating Fig. 4 is a plan view of another form of conthe bimetal 444 without passing through the bitrol similar to that shown in Fig. 1. metal 444. Current will also pass through the In the figures of the drawings, a form of conheater 462 and through the upper leg 46! of the trol is shown in which a simple U-shaped permabimetal, 460 to the movable starting contact 410:

from which current will flow through the connector 455, the conductor 482 and the starting or phasa nnding 424. Current will also flow through the pig-tail connection 454, the connector 455, the conductor 48B and the main winding 422 to the supply conductor 425. This will cause the upper leg 45! of the bimetal 450 to be heated and curl to the right as shown in Fig. 1 until the movable contact 415 engages the back contact 415. The bimetal leg 45i will creep to momentarily separate the contacts 410 and 415 to supply sufficient heat to the bimetal leg 45| to keep the contact 410 separated from the contact 478.

The lower leg 459 of the bimetal 465 will compensate the starting control for changes in environment temperature since any extraneous heating efiect upon the leg 45l will provide a compensating heating effect upon the leg 459.

Inasmuch as this bimetal 460 is intended to operate at low temperatures, such a compensation is desirable.

For this control, I have provided a simple means providing a snap action for both the starting and overload controls and in addition this same means is employed to insure that if the overload contacts open and the starting contacts open, both are reset simultaneously. To do this, I have provided the armatures 52l and 523 at the upper end of the leg 46l of the bimetal 465 and of the bimetal 444. These armatures are located between the legs of a U-shaped permanent magnet 525 which is fastened to the base 434 by the bracket 521. These armatures are, of course, some suitable magnetic material such as soft iron and are provided with extensions which are long enough so that in case the overload protector bimetal 444 trips to the open position to open the overload contacts, the armature 523 will engage the armature 52! when it is holding the contact 415 in engagement with the contact 415, or very nearly so.

With this arrangement not only will each of the armatures snap away from their respective leg of the U-shaped permanent magnet with a suitable snap action, but the armatures SH and 523 will stick together until there is a sufllciently powerful force provided by the cooling of either or both bimetals to separate the armatures 52! and cause both bimetals to move to their starting positions which is shown in Fig. 1.

In Fig. 4 there is shown another form which may be used to carry out this same magnetic principle. In this form the U-shaped permanent magnet 525 is mounted upon the base 534 of insuiating material. Also mounted upon the base 554 are the cantilever supported bimetal members 551 and 544 which correspond to the bimetals "I and 444. The bimetal 55| at its upper end carries the armature 52L while the bimetal 544 at its upper end carries the armature 623. When the bimetals are cool, these armatures rest directly against the inside of the legs of the U-shaped permanent magnet so that only a very sm:. .1 comparative weak permanent magnet is required to produce the desired snap action for the movable contacts 515 and 542 which are carried by the bimetals.

In order to insure that in case both bimetals trip open that they will reset simultaneously, a third armature 525 is provided between the armatures 52! and 523 so as to provide a connecting path for the flux between the armatures SM and 523. This armature 525 is supported upon one end of a leaf spring 525, the other end of which is anchored to the base 534. With this arrangement when both of the bimetals 5H and 444 snap away from the legs of the permanent magnet 525 to open the contacts 510 and 542, they will engage the armature 525 and will remain magnetically connected until by the cooling of the bimetals 55! and 544 sufficient force is created to cause all the armatures to separate and return to the position shown in Fig. 4.

By making the starting bimetal of proper crosssection and length by operating it at a high temperature and by properly adjusting it through the set-screw 58, ideal starting time conditions can be obtained for the motor even with wide variations in room temperature conditions as well as wide variations in voltage. The control may accommodate various sizes and types of motors by varying the width, thickness, length, column loading and material of the bimetal strips, and/or the relationship to the contacts and the heaters. The relay may be mounted in any desired position and may be used for 25, or cycle standard currents. The control is adequately compensated for all changes in room temperatures and is made of a few simple parts which may be made without expensive tools and the entire control may be manufactured and assembled at a low cost. It may be made in very small sizes and has no starting hum. The back contact reduces the voltage drop through the starting control after the starting period of the motor and prevents overheating of the starting bimetal.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

' hat is claimed is as follows:

'- 1. A control including a plurality of mo!able.

means, each or said movable ngsans includinma portion of magnetic material, means fonmount-r.

ing said movable means to hold said portions of magnetic material in alignment for movement into contact with and away from each othersi hes arate independent flow control deyicegihdi r'ii ually operable by two of said movable means when said two movable means each reac redetermined position away from each other,,magnetic means having poles located beyond the limit of movement of said portions of magnetic material to form a magnetic field thijiifiliknit.thisw path in which said portions of maghetidmate:

rial operate for providing a magneticgiorcotov hold said two movable means in saicl predetern.

mined positions and to cause the portior 1 s gf magnetic material to be attracted to e 5 other when both leave said predetermined ngsifii'fii? and move toward each other and alsojto caus said portions of magnetic material torotumsimultaneously to said predetermined positions when this attraction is overcome.

2. A control including a plurality of strip portions mounted for movement toward and away from each other, each of said strip portions being provided with a piece of magnetic material, said pieces of magnetic material being located on said strip portions so as to have aligned paths of movement into contact with and away from each other, two of said strip portions carrying a switch contact, a cooperating contact for each of said switch contacts located to be contacted by the switch contacts upon reaching a limit of movement away from each other, magnet means located immediately beyond the limit of movement of two of the magnetic pieces away from 3. A control including a plurality of movable when said two movable means are in said positions.

5. A control including two movable bimetal strip portions each provided with apie ce qtmaw netic material, means for mountingisailnortiqns so that said pieces move in substantiaLalignment into contact with and away from eaclrpther am U-shaped permanent magnet extending amundlml said pieces and having its pole areas-loaed means, each of said means including a portion of magnetic material, means for mounting said movable means to hold said portions in alignment in directly beyond the limits of movement pithenfor movement into contact with and away from pieces away from each other, and separate inde=..

each other, two of said mounting means includpendent flow control devices operably connected ing individual actuating means, separate indeto said strip portions.

pendent flow control devices individually oper- HARRY F. CLARK.

able by two of said movable means upon reaching a predetermined position away from each other, REFERENCES CITED permanent magnet means havmg areas The following references are of record in the sitioned directly beyond two of said portions fil f this patent;

when said two movable means are in said positions to provide a magnetic force to hold said UNITED STATES PATENTS two movable means in said positions and to pro- Number Name t vide a magnetic field throughout the path in 276,702 Moses May 1, 33

which said portions op r 1,339,900 Lewis May 11, 1920 4. A control including a plurality of mova le 1,317,592 sokolofl Aug, 4, 1931 means, ch of said means including a portion 1,978,737 ,Bowers et a1. Oct. 30, 1934 of magnetic material, means for mounting said 2,153,233 Kuhn May 16, 1939 movable means to hold said portions in align- 2,175,032 Schaefer t 3, 1939 ment for movement into contact with and away 2,295,340 Fiene t, 3, 1942 from each other, two of said mounting means 2,300,41 H n 3, 1942 including individual actuating means, separate ,302,250 Penn Nov, 7, 942

independent flow control devices individually operable by two of said movable means upon reach- FOREIGN PATENTS ing a predetermined position away from each Number Country Date other, a U-shaped permanent magnet having its 74,945 Sweden Aug. 23, 1929 yoke extending around said portions and its poles 294,631 Italy Mar. 31, 1932 positioned directly beyond two of said portions 392,490 Great Britain May 18, 1933 l v Q- i 

